2-Heptyl-3-hydroxy-4(1H)-quinolone (PQS), a compound
from P. aeruginosa, functions as both a quorum sensing
(QS) regulator and a potent iron chelator to induce expression of
pyoverdine and pyochelin which are involved in high-affinity iron
transport systems. A potential dual-acting antibiofilm strategy requires
molecules designed to interfere with iron uptake and the QS system
of P. aeruginosa. A series of 2-substituted 3-hydroxy-1,6-dimethylpyridin-4-ones
have been designed, synthesized, and tested as biofilm inhibitors
of P. aeruginosa. One compound, N-((1,3,6-trimethyl-4-oxo-1,4-dihydropyridin-2-yl)methyl)hexanamide
(10d), exhibits 68.67% biofilm inhibitory activity at
20 μM. Further mechanistic studies have confirmed that this
compound not only inhibits the QS systems of P. aeruginosa but also acts as an iron chelator to compete strongly with pyoverdine,
causing iron deficiency in bacteria. The pyoverdine receptor FpvA
was revealed as the target of 10d by the Pvds mutant strain, fpvA-overexpressed strain, and in silico studies.
Silver nanostructures of different morphologies including well-defined dendrites were synthesized on an Au substrate by a simple surfactant-free method without using any template. The morphology of the material was investigated by field-emission transmission electron microscopy and scanning electron microscopy. The crystal nature of the dendritic nanostructure was revealed from their X-ray diffraction and electron diffraction patterns. Effects of applied potential, electrolysis time, and the solution concentration were studied. The possible formation mechanism of the dendritic morphology was discussed from the aspects of kinetics and thermodynamics based on the experiment results. The H(2)O(2) electroreduction ability of the dendritic materials was characterized. Use of silver dendrite-modified electrode as H(2)O(2) sensor was also demonstrated.
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